36 U. S. P. R. R. EXP. AND SURVEYS— ZOOLOGY-—GENERAL REPORT. 
Sub-Family MILVINAE.—The Kites. 
Size various, usually medium or small. General form usually rather slender and not strong ; wings and tail usually long; bill 
short, weak, hooked, and acute ; tarsi and toes usually slender and not strong, sometimes short. The birds of this group habitually 
feed on reptiles and other smal] animals, and are deficient in the strength and courage of the other groups of the falcons. 
NAUCLERUS, Vigors. 
Nauclerus, Vicgors, Zool. Jour. Il, p. 3&6, (1825.) 
Wings and tail very long, the former pointed, the latter deeply forked. Bill short, but moderately strong ; tarsi short ; toes short. 
Contains three species—two American and one African. 
NAUCLERUS FURCATUS, Linnaeus. 
Tne Swallowstailed Hawk. 
‘alco fureatus, Linn. Syst. Nat. I, 129, (1766.) 
Ficures.—Catesby Nat. Hist. Carolina, Birds, pl. 4; Buffon Pl. Enl. 72; Wilson Am. Orn. VI, pl. 51, fig.3; Aud. B. of 
Am. pl. 72. Oct. ed. I, pl. 18; Gould B. of Eur. I, pl. 30; De Kay Nat. Hist. New York, Birds, pl. 7, fig. 15. 
Wings and tail long, the latter deeply forked. Head and neck, under wing coverts, secondary quills at their bages, und entire 
under parts, white. Back, wings, and tail black, with a metallic lustre ; purple on the back and wing coverts ; green and bluo 
on other parts. Tarsi and toes greenish blue ; bill horn color. 
Total length, female, 23 to 25 inches ; wing, 16 to 17; inches; tail, 14 inches. Male rather smaller. 
Hab.—Southern States on the Atlantic, and centrally northward to Wisconsin. Texas, (Mr. Audubon,) Wisconsin, (Dr. Hoy,) 
Pennsylvania, (Mr. Krider.) Accidental in Europe. Spec. in Nat. Mus., Washington, and Mus. Acad., Philadelphia. 
The most handsome of the North American birds of this group, and possessing very graceful 
flight. It is abundant in the southern States, and occasionally strays as far north as the 
vicinity of Philadelphia, a very fine specimen having been obtained this year (1857) near that 
city by Mr. John Krider. 
List of specimens. 
eS S Measurements. 
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Louisiana. 
ELANUS, Savigny. 
Elanus, Savieny, Nat. Hist. Egypt I, p. 97, (1809.) 
Wings long, pointed ; tail moderate, emarginated ; tarsi short. Bill short, compressed, hooked. Size medium or small, and 
general form adapted to the capture of reptiles, insects, and other defenceless animals. 
